Thus, if GSX has to disable FSX default vehicles, then I lose a perfectly good, functional, and (in other non-airport AI traffic-areas) more-useful product, in place of one that ONLY address user-related aircraft and airport AI.
GSX doesn't disable anything OUTSIDE the parking you just selected with it.
It's our SCENERIES (this was the reason of the original question, btw) that always had to disable default FSX vehicles by flagging their parking stands in the AFCAD, since they provide their own, which looks usually better and more in tone with the scenery, but are static, and this saves a significant amount of frame rate too.
So, GSX doesn't have anything to do with this, it's the sceneries that have been designed for this, and for good reasons: people *hate* when they see something "default" in a scenery (the otherwise perfectly good KMCO was unfairly destroyed in pieces because of this), the default GSX ground vehicles are quite dumb in operation, we can't obviously count on users installing replacement models, they would keep being dumb, even if you replace them with repaints, and they also affect fps quite significantly.
This could be potentially a problem with GSX too, since even GSX (right now) might have trouble disabling our ground static vehicles, unless we made the scenery in a way that it would be easy for GSX to disable things at the selected parking, which has been done in some places at KDFW and more thoroughly at KLAX.
Future sceneries will be designed more and more around GSX, since we can be reasonably sure that every FSDT user will download it, since it's free...
To better answer your question: it's something the sceneries are doing, so I'm afraid repaints of default vehicles won't appear on our sceneries, and this doesn't have anything to do with GSX.
To better answer the original question of being hard to guess the type or parking when everything is flagged as "Ramp", we can fix this easily with GSX and it was already implemented somewhat with ParkMe: we can override the parking name used by the AFCAD and replace it with our own description in the GSX parking selection menu.
It would be enough to add a feature to *go* there, so GSX could be used as a positioning method instead of the default "Go To Airport" menu, and it would be even easier to use, since in GSX parkings can be grouped by terminal so, instead of having a long list which is difficult to scroll as the default menu, the pages are much shorter, because you first select a Terminal, then a parking. And, since it uses the in-flight ATC-style menu, you could be able to reposition without opening the main FSX menu.